Update versions of downloadable dependencies

Versions changes: GMP 4.3.2 -> 5.1.3, MPFR 2.4.2 -> 3.1.2.

Fix invalid date in changelog for previous commit.

Signed-off-by: Anton Kolesov <anton.kolesov@synopsys.com>
(cherry picked from commit 67601cc716832f529a2aaa94639c7911afe28dfb)